The present invention relates to vehicles having a drag reduction fairing and, more particularly, to aircraft having a drag reduction fairing.
Protrusions extending from surfaces of a vehicle cause drag when the vehicle moves. How much drag is caused by a protrusion is related to a shape and size of the protrusion, a shape of the vehicle, and a position and orientation of the protrusion on the vehicle. Higher amounts of drag are caused by protrusions that do not have a streamlined aft end (e.g., the aft end includes a generally vertical wall extending perpendicular to a direction of vehicle motion) because turbulent separation of airflow develops behind the aft end of the protrusion. Under some circumstances, a high-frequency oscillating vortex pattern, known as a von Karman vortex street, may develop behind the protrusion. von Karman vortex streets increase drag and may increase interior vehicle noise.
Higher amounts of drag results in lower fuel efficiency. Lower fuel efficiency necessitates an increase in block fuel, the added weight of which also decreases fuel efficiency, or a payload reduction to achieve comparable flight distances. One solution for reducing drag is to replace non-streamlined protrusions with streamlined protrusions. However, replacing entire protrusions can be a costly endeavor.
A type of protrusion commonly used on aircraft is an anti-collision light. Because federal aviation regulations require that anti-collision lights be visible in a 360° pattern around aircraft, any streamlining feature added adjacent to or as part of the anti-collision light must allow light to pass through it. A cost effective device for improving drag characteristics of new and in-service vehicles having a protrusion is needed.